1. Field of the Invention
The present invention is directed broadly to microelectromechanical systems (MEMS) and more particularly to a microelectromechanical structure which is particularly useful for data storage applications.
2. Description of the Background
The ability of scanning tunneling microscopy ("STM") to modify surfaces on a nanometer scale has been demonstrated in a variety of experiments dating back to the early development of the instrument. Initial efforts focused on the application of mechanical force between the surface and the tip. The ultimate resolution of mechanical manipulation with an STM probe was demonstrated by Eigler and Schweizer who were able to arrange individual xenon atoms to form the letters "IBM" on a nickel surface in a cryogenic vacuum chamber. When an STM tip is held in tunneling or field emission range, voltage pulses applied to the tip can induce surface changes in a non-contacting mode by various physical mechanisms, e.g., heating, material deposition, or field evaporation of material from the tip. Gas molecules ionized by the high electric field at the tip are accelerated toward the sample where they impact with sufficient kinetic energy to remove atoms from the first several atomic layers. The ability of the STM to modify surfaces has led to the investigation of the use of that technology for storing, reading, and writing bits of data.
Some of the storage methods explored to-date have been rewritable, but most have been write once. However, nearly all of the reported techniques have been extremely limited in their ability to write data (on the order of Kb/s) because detailed mechanical motion was required to create or detect bits.
The need therefore exists to construct the components necessary to build a microelectromechanical memory device, using standard fabrication techniques, which can achieve commercially viable storage capacities, i.e. 10 GB in a 1 centimeter by 1 centimeter by 0.2 centimeter volume. To achieve such a device, several problems must be overcome including the ability to precisely fabricate a cantilevered beam which can act as an STM probe. It is also necessary to overcome the problem of how the probe can be precisely positioned for read and write operations.